Mexico is sending more troops and police to try to control drug violence that has spiralled into warfare along the US border.

The goal of Co-ordinated Operation North East was to reinforce government authority in the two states most heavily affected by a surge in violence following a split between the Gulf and Zetas drug gangs, federal police spokesman Alejandro Poire said.

The new effort also aims to keep the two cartels from regrouping after the takedown of key leaders. But in a media briefing with all government security officials and governors of Nuevo Leon and Tamaulipas, the affected states, Mr Poire provided no details or numbers of reinforcements and answered no questions.

Intense cartel violence has plagued the industrial city of Monterrey in Nuevo Leon and all of Tamaulipas, where cartel firefights and violence this month sent residents fleeing the once-picturesque tourist town of Ciudad Mier and where 72 migrants were found slaughtered earlier this year.

Tamaulipas shares 560 miles of Texas border, with some of the busiest border crossings in the world - Nuevo Laredo across from Laredo, Reynosa across from McAllen and Matamoros across from Brownsville.

Governor Eugenio Hernandez said his state had been a major transport corridor for organised crime since prohibition, when the US outlawed alcohol in the 1920s into the early 30s. "But the situation has recently become much more complicated," he said. "It's greatly affected the dynamic of our state."

Mr Poire touted recent government blows against the two cartels, including the killing earlier this month of Gulf cartel leader Antonio "Tony Tormenta" Cardenas Guillen and the 2008 capture of a founding member of the Zetas, Jaime "the Hummer" Gonzalez Duran, who was sentenced for money laundering and weapons possession earlier this year.

The government already has similar operations in other parts of Mexico, including Chihuahua state, where the border city of Ciudad Juarez across from El Paso, Texas, is considered one of the most violent cities in the world.

Such efforts so far have failed to quell drug violence, which has killed 28,000 people since President Felipe Calderon launched his offensive on organised crime in late 2006. An opinion poll released this week said 49% of Mexicans believed the government's drug war had been a failure, compared with 33% who said it has been a success.